Breaks in rugby strip playing outside (7)
I believe the answer is:
irrupts
'breaks in' is the definition.
(I've seen this before)
'rugby strip playing outside' is the wordplay.
'rugby' becomes 'ru'.
'playing' indicates anagramming the letters.
'outside' is an insertion indicator.
'strip' with letters rearranged gives 'irpts'.
'ru' inserted inside 'irpts' is 'IRRUPTS'.
(Other definitions for irrupts that I've seen before include "Breaks in" , "Bursts into, enters forcibly" , "Stirrup? (anag)" , "Makes a sudden entry or invasion" .)