A mind to be in the lead (5)
I believe the answer is:
ahead
'be in the lead' is the definition.
(synonyms)
'a mind' is the wordplay.
'mind' becomes 'head' (synonyms).
'a'+'head'='AHEAD'
'to' acts as a link.
(Other definitions for ahead that I've seen before include "in van" , "likely to win?" , "In the lead, in advance" , "Winning" , "In front as in race" .)