Lifting device, one crushed by dense liquid (10)
I believe the answer is:
dumbwaiter
'lifting device' is the definition.
(dumbwaiter is a kind of lifting device)
'one crushed by dense liquid' is the wordplay.
'one' becomes 'I' (Roman numeral).
'crushed by' indicates putting letters inside.
'dense' becomes 'dumb' (synonyms).
'liquid' becomes 'water' (water is a kind of liquid).
'dumb'+'water'='dumbwater'
'i' inserted into 'dumbwater' is 'DUMBWAITER'.
(Other definitions for dumbwaiter that I've seen before include "Small lift for food" , "Food table, lift" .)