Persistent rain in Galway limits exercise (8)
I believe the answer is:
training
'exercise' is the definition.
(thesaurus)
'persistent rain in galway limits' is the wordplay.
'limits' says the answer is hidden in the clue (the answer is surrounded or limited by the clue).
'TRAINING' is hidden within 'persistent rain in galway'.
(Other definitions for training that I've seen before include "in practice" , "Coaching" , "Doing exercises" , "Tuition" , "Regime" .)