Ties up, as engines losing temperature (5)
I believe the answer is:
moors
'ties up' is the definition.
(as in mooring a boat)
'engines losing temperature' is the wordplay.
'engines' becomes 'motors' (I've seen this in another clue).
'losing' is a deletion indicator.
'temperature' becomes 't' (abbreviation).
'motors' with 't' taken away is 'MOORS'.
'as' is the link.
(Other definitions for moors that I've seen before include "Secures" , "Ties up a boat" , "wild areas" , "Open heathlands" , "wild places" .)