Pet worries saint (6)
I believe the answer is:
caress
'pet' is the definition.
(thesaurus)
'worries saint' is the wordplay.
'worries' becomes 'cares' (I've seen this before).
'saint' becomes 's'.
'cares'+'s'='CARESS'
(Other definitions for caress that I've seen before include "Embrace with affection" , "Scares with loving gesture" , "Scares with loving stroke" , "Stroke gently" , "Stroke affectionately" .)