Worn out, the nurses scan unit for pressure (10)
I believe the answer is:
threadbare
'worn out' is the definition.
(I've seen this before)
'the nurses scan unit for pressure' is the wordplay.
'nurses' means one lot of letters goes inside another (nurse can mean to hold onto or harbour).
'scan' becomes 'read' (synonyms).
'unit for pressure' becomes 'bar' (scientific unit).
'read'+'bar'='readbar'
'the' placed around 'readbar' is 'THREADBARE'.
(Other definitions for threadbare that I've seen before include "Frayed" , "Thin, tattered, worn out" , "the worse for wear" , "poor" , "Well-worn" .)