The last fathead to use a bent nail (5)
I believe the answer is:
final
'the last' is the definition.
(I've seen this before)
'use a bent nail' is the wordplay.
'use' becomes 'f' (I am not sure about this - if you are sure you should give a lot more credence to this answer).
'a bent' is an anagram indicator.
'nail' is an anagram of 'inal'.
'f'+'inal'='FINAL'
'fathead to' acts as a link.
This may not be right. Some or all of it may belong to 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" .)