The last fathead to use a bent nail (5)
I believe the answer is:
final
'the last' is the definition.
(I've seen this in another clue)
'use a bent nail' is the wordplay.
'use' becomes 'f' (I am not sure about this - if you are sure you should believe this answer much more).
'a bent' is an anagram indicator.
'nail' anagrammed gives 'inal'.
'f'+'inal'='FINAL'
'fathead to' acts as a 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 final that I've seen before include "big match" , "Conclusive" , "Last in a series of games or contests" , "Last match in a competition" , "Concluding" .)