Mackintosh of Imachar (3)
I believe the answer is:
mac
'mackintosh' is the definition.
(synonyms)
'of imachar' is the wordplay.
'of' says the answer is hidden in the clue.
'MAC' is hidden in the letters of 'imachar'.
(Other definitions for mac that I've seen before include "A rainproof" , "Waterproof coat (colloq.)" , "Coat - computer" , "PC" , "laptop?" .)