Arouse wife on the ground (4)
I believe the answer is:
whet
'arouse' is the definition.
(as in whetting someone's appetite)
'wife on the ground' is the wordplay.
'wife' becomes 'w' (abbreviation).
'on' is an insertion indicator.
'ground' indicates anagramming the letters ('grind' the letters into a new form).
'the' anagrammed gives 'het'.
'w' inserted into 'het' is 'WHET'.
(Other definitions for whet that I've seen before include "Hone" , "Sharpen the blade of (a tool/weapon)" , "Edge" , "'Sharpen, appetite say (4)'" , "Excite" .)