Lovatts Colossus 168. Giant Cryptic

5a. Infants' food one's taken into the car racing? (7,3). MACHINE???
formula one
19a. Smell of duck severe (5). OUDOR (maybe)
odour , the oudor duck is the cryptic clue
25. Told to purchase more presently (2,3 2). BYANDBY. (Maybe)
by and by
47. Half of Columbia's capital is swampland (3). ?O?
bog
53. Veer around the leader an old-timer revealed (7)
observe is the only answer i can muster
68. Left to proceed to the north-east with the wind? (4). G??? (Gust or Gale maybe no sure)
gone
73. What some lacklustre men do? Use whatever is awe-inspiring. T?????D?U?
tremendous
6d. Bedouin holding agreement for the French (3). ??I
oui
7d. Degree to which Scot may be pet for British newspaper. (6). ??S???
mascot (british newspaper lol)
8d. One doing watches for British newspaper (8) ??????E? GAZETTES (maybe)
guardian
15d. Bing to take on task of filleting fish (6). ???I?G
boning
17d. Necessary to make new bee den (4,2) N?E???
need be
49d. Avoid responsibility when there's no police presence (3,3). ???OUT
cop out
54d. Heard a windmill blade used in attack (6). ??S?I?
assail
56d. Coming in to captivate (8). ?R?R????
entrance

Thank you for all your help, however you perhaps don't have this puzzle as I couldn't get some of your answers to fit, in some cases my cross words were incorrect so it was very helpful to see where I had gone wrong.
These are the answers that I worked out to the others:

53a. =. VETERAN
8d. =. OBSERVER
Once again thank you and I hope these answers can help others, good luck
Cheers
Smithy