Inside centre, a trained nurse (5)
I believe the answer is:
treat
'nurse' is the definition.
(thesaurus)
'inside centre a trained' is the wordplay.
'inside' indicates a hidden word.
'TREAT' is hidden within 'centre a trained'.
(Other definitions for treat that I've seen before include "Something that causes special pleasure or delight" , "Delightful outing; pay for (someone else)" , "Care for medically" , "Deal with - delightful surprise" , "Try to heal" .)