Happiness alien to criminal (7)
I believe the answer is:
elation
'happiness' is the definition.
(elation can mean intense happiness)
'alien to criminal' is the wordplay.
'criminal' indicates an anagram.
'alien'+'to'='aliento'
'aliento' anagrammed gives 'ELATION'.
(Other definitions for elation that I've seen before include "There's great joy" , "'High spirits, exhilaration (7)'" , "Transport" , "Feeling of joy and pride" , "Delight, ecstasy" .)