Let go and slip out emergency exit (4,6)
I believe the answer is:
fire escape
'emergency exit' is the definition.
(synonyms)
'let go and slip' is the wordplay.
'let go' becomes 'fire' (both can mean to dismiss from a job).
'and' means one lot of letters go next to another.
'slip' becomes 'escape' (I've seen this before).
'fire'+'escape'='FIRE-ESCAPE'
'out' acts as a link.
(Other definitions for fire escape that I've seen before include "Emergency exit" , "steps outside" , "it could be a life-saver" , "Emergency flight perhaps" , "Evacuation staircase" .)