It's no good just being one in front (4)
I believe the answer is:
vain
'it's no good' is the definition.
(I've seen this before)
'one in front' is the wordplay.
'one' becomes 'i' (roman numeral).
'in' indicates putting letters inside.
'front' becomes 'van' (I've seen this before).
'i' put inside 'van' is 'VAIN'.
'just being' is the link.
I am not very happy about this link. Some or all of it may be part of another bit of the clue.
Can you help me to learn more?
(Other definitions for vain that I've seen before include "being a big-head" , "without success" , "Worthless" , "Conceited or unsuccessful" , "Conceited or unavailing" .)