Most of detachment love Irish tank (9)
I believe the answer is:
reservoir
'tank' is the definition.
(I've seen this before)
'most of detachment love irish' is the wordplay.
'most of' means to remove the last letter.
'detachment' becomes 'reserve'.
'love' becomes 'o' (In tennis, 'love' means 'zero').
'irish' becomes 'ir' (abbreviation).
'reserve' with its last letter taken off is 'reserv'.
'reserv'+'o'+'ir'='RESERVOIR'
(Other definitions for reservoir that I've seen before include "River rose (anag.)" , "Large water store" , "Store for water etc" , "Area for storage, of water say" , "Lake for collecting and storing water" .)