University creep Kelvin lost in part of labyrinth (7)
I believe the answer is:
utricle
'part of labyrinth' is the definition.
(part of the labyrinth in the ear)
'university creep kelvin lost' is the wordplay.
'university' becomes 'u' (abbreviation for university).
'creep' becomes 'trickle' (both can mean to arrive gradually).
'kelvin' becomes 'K' (abbreviation for the unit of temperature).
'lost' is a deletion indicator.
'trickle' with 'k' taken away is 'tricle'.
'u'+'tricle'='UTRICLE'
'in' is the link.
(Other definitions for utricle that I've seen before include "Part of the internal ear" , "bag" , "Cell" .)