Exploit is pointless with no leader outside (7)
I believe the answer is:
utilise
'exploit' is the definition.
('exploit'->'utilize' is in my internal thesaurus and 'ize'->'ise')
'is pointless with no leader outside' is the wordplay.
'pointless' becomes 'futile' (I've seen this before).
'with no leader' means to remove the first letter.
'outside' indicates putting letters inside.
'futile' with its initial letter removed is 'utile'.
'is' put within 'utile' is 'UTILISE'.
(Other definitions for utilise that I've seen before include "Find application or task for" , "Employ, make use of" , "Put to use" , "Employ, do something with" , "Put into service, find application for" .)