Off-putting remedy, a kind the Gunners pity, not having it (8,7)
I believe the answer is:
aversion therapy
'off-putting remedy' is the definition.
(psychological treatment)
'a kind the gunners pity not having it' is the wordplay.
'kind' becomes 'version' (version is a kind of kind).
'gunners' becomes 'RA' (Royal Artillery).
'not having' indicates named letters should be taken away.
'pity' with 'it' removed is 'py'.
'a'+'version'+'the'+'ra'+'py'='AVERSION THERAPY'
(Other definitions for aversion therapy that I've seen before include "Type of treatment" , "Medical treatment" , "Behaviour modification technique" , "addict's treatment" .)