Tried shaking head in fatigue (9)
I believe the answer is:
tiredness
'fatigue' is the definition.
(I know that fatigue can be written as tiredness)
'tried shaking head' is the wordplay.
'shaking' indicates an anagram.
'head' becomes 'ness' (ness is a headland).
'tried' anagrammed gives 'tired'.
'tired'+'ness'='TIREDNESS'
'in' acts as a link.
(Other definitions for tiredness that I've seen before include "Weariness" , "Weary feeling" , "Exhaustion" , "Residents in state of fatigue" , "Lassitude; residents (anag.)" .)