Tried God with AA for treatment after hospital (3,1,2)
I believe the answer is:
had a go
'tried' is the definition.
(I've seen this before)
'god with aa for treatment after hospital' is the wordplay.
'with' is a charade indicator (letters next to each other).
'for treatment' indicates an anagram (I've seen this in other clues).
'after' says to put letters next to each other.
'hospital' becomes 'h'.
'god'+'aa'='godaa'
'godaa' is an anagram of 'adago'.
'adago' after 'h' is 'HAD A GO'.
(Other definitions for had a go that I've seen before include "Made an attempt" , "Tried" .)