Action from former single in bed (7)
I believe the answer is:
'action' is the definition.
(exploit is a kind of action)
'former single in bed' is the wordplay.
'former' becomes 'ex' (prefix meaning former or onetime).
'single' becomes 'I' (one).
'in' indicates putting letters inside.
'bed' becomes 'plot' (a bed or plot of land).
'i' inserted within 'plot' is 'ploit'.
'from' is the link.
(Other definitions for exploit that I've seen before include "Milk" , "Benefit from" , "Heroic deed" , "Make capital out of" , "Capitalise on, take advantage of" .)