Get ahead when appropriate, overtaking second (7)
I believe the answer is:
prosper
'get ahead' is the definition.
(synonyms)
'appropriate overtaking second' is the wordplay.
I cannot really understand how this works, but
'second' could be 's' (common abbreviation) and 's' is present in the answer.
'appropriate' could be 'proper' (similar in meaning) and 'proper' is found in the remaining letters.
No letters remain.
This explanation may well be incorrect...
'when' is the link.
Can you help me to learn more?
(Other definitions for prosper that I've seen before include "Flourish, do well" , "Go well" , "like Merimee, nominally" , "Get rich" , "Succeed, flourish" .)