Lieutenant found in precipitous place of refuge (7)
I believe the answer is:
shelter
'place of refuge' is the definition.
(I've seen this before)
'lieutenant found in precipitous' is the wordplay.
'lieutenant' becomes 'lt'.
'found in' means one lot of letters goes inside another.
'precipitous' becomes 'sheer' (I've seen this before).
'lt' placed inside 'sheer' is 'SHELTER'.
(Other definitions for shelter that I've seen before include "Shield as from rain" , "Place of refuge" , "Cover, protection" , "Refuge or protective cover" , "Monk's hood" .)