Cut off in one end of Trump Tower without retiring (9)
I believe the answer is:
interrupt
'cut off' is the definition.
(synonyms)
'in one end of trump tower without retiring' is the wordplay.
'one end of' indicates one should take the final letters.
'tower' becomes 'turret' (turret is a kind of tower).
'without' indicates putting letters inside.
'retiring' says the letters should be written in reverse.
The last letter of 'trump' is 'p'.
'p' put within 'turret' is 'tpurret'.
'tpurret' backwards is 'terrupt'.
'in'+'terrupt'='INTERRUPT'
(Other definitions for interrupt that I've seen before include "Break the continuity of" , "middle of ashtray after burning slip gets put out" .)