Court an NCO with love (3)
I believe the answer is:
woo
'court' is the definition.
(both can mean to romance someone)
'an nco with love' is the wordplay.
'an nco' becomes 'wo' (warrant officer, type of non-commissioned officer).
'with' is an insertion indicator.
'love' becomes 'o' (love means zero in tennis).
'wo' going around 'o' is 'WOO'.
(Other definitions for woo that I've seen before include "Pay court to" , "Court, seek to marry" , "Court; importune" , "Do courting" , "Try to get the girl?" .)