In any case there's no trouble (5)
I believe the answer is:
annoy
'trouble' is the definition.
(thesaurus)
'in any case there's no' is the wordplay.
'in' indicates putting letters inside.
'case' means to remove the middle letters.
'there's' becomes 'n' (I've seen this in other clues).
'any' with its middle taken out is 'ay'.
'n'+'no'='nno'
'ay' going around 'nno' is 'ANNOY'.
(Other definitions for annoy that I've seen before include "Gall" , "Upset" , "eat" , "Irritate, nettle" , "get angry" .)