NCO wears twill and nicely tailored tops (8)
I believe the answer is:
sergeant
'nco' is the definition.
(I've seen this before)
'twill and nicely tailored tops' is the wordplay.
'twill' becomes 'serge' (I've seen this in another clue).
'tops' suggests taking the first letters.
The initial letters of 'and nicely tailored' is 'ant'.
'serge'+'ant'='SERGEANT'
'wears' is the link.
This may not be right. It may be part of another bit of the clue.
Can you help me to learn more?
(Other definitions for sergeant that I've seen before include "NCO or police officer ..." , "Copper" , "NCO; Death a fell one, Hamlet" , "Army rank" , "Man in charge" .)