Last fellow to break nail (5)
I believe the answer is:
final
'last' is the definition.
(I know that last can be written as final)
'fellow to break nail' is the wordplay.
'fellow' becomes 'f' (abbreviation - of a society etc.).
'to break' is an anagram indicator.
'nail' anagrammed gives 'inal'.
'f'+'inal'='FINAL'
(Other definitions for final that I've seen before include "Concluding" , "big match" , "Last, ultimate" , "Not to be altered" , "The last exam or leg of competition" .)