Exhausted and tense, rest head uneasily (9)
I believe the answer is:
shattered
'exhausted' is the definition.
(I've seen this before)
'tense rest head uneasily' is the wordplay.
'tense' becomes 't' (abbreviation used in many dictionaries).
'uneasily' indicates an anagram.
't'+'rest'+'head'='tresthead'
'tresthead' is an anagram of 'SHATTERED'.
'and' is the link.
(Other definitions for shattered that I've seen before include "Broke into tiny pieces" , "Greatly upset; broken" , "Done in" , "Broken into sharp pieces" , "devastated" .)