Creepy posh governess nurses cold (7)
I believe the answer is:
uncanny
'creepy' is the definition.
(thesaurus)
'posh governess nurses cold' is the wordplay.
'posh' becomes 'u' (abbreviation for upper-class - opposite to non-u).
'governess' becomes 'nanny'.
'nurses' is an insertion indicator (nurse can mean to hold onto or harbour).
'cold' becomes 'c' (eg on taps).
'nanny' placed around 'c' is 'ncanny'.
'u'+'ncanny'='UNCANNY'
(Other definitions for uncanny that I've seen before include "Strange, beyond the normal" , "Weird, unnatural" , "Weird - strange" , "Weird; supernatural" , "Weird, unearthly" .)