Gush about husband's treatment under hospital department (7)
I believe the answer is:
enthuse
'gush' is the definition.
(I've seen this in another clue)
'husband's treatment under hospital department' is the wordplay.
'husband' becomes 'h' (abbreviation).
'treatment' becomes 'use' (I've seen this in another clue).
'under' means one lot of letters go next to another (below, in a down clue).
'hospital department' becomes 'ENT' (abbreviation for Ear, Nose and Throat department).
'h'+'use'='huse'
'huse' after 'ent' is 'ENTHUSE'.
'about' is the link.
(Other definitions for enthuse that I've seen before include "Seem keen" , "Show lively interest and keenness" , "Excite - show excitement" , "Gush in praise" , "Show strong approval" .)