Number getting into some trouble (5)
I believe the answer is:
annoy
'trouble' is the definition.
(I've seen this before)
'number getting into some' is the wordplay.
'number' becomes 'no' (abbreviation for 'number').
'getting into' is an insertion indicator.
'some' becomes 'any' (similar in meaning).
'no' placed inside 'any' is 'ANNOY'.
(Other definitions for annoy that I've seen before include "Make slightly angry" , "be a nuisance" , "Bug, rile" , "trouble" , "Irritate - pester" .)