Trust answer entertained by suitable husband (5)
I believe the answer is:
faith
'trust' is the definition.
(synonyms)
'answer entertained by suitable husband' is the wordplay.
'answer' becomes 'a' (abbreviation eg in Q and A).
'entertained by' is an insertion indicator (inserted letters are hosted or entertained).
'suitable' becomes 'fit' (similar in meaning).
'husband' becomes 'h' (abbreviation).
'a' going within 'fit' is 'fait'.
'fait'+'h'='FAITH'
(Other definitions for faith that I've seen before include "'..... will move mountains'" , "Staunch trust" , "It goes with hope and charity" , "Confidence" , "Total trust" .)