Mean to claim head off court servant (7)
I believe the answer is:
average
'mean' is the definition.
('average' can be a synonym of 'mean')
'claim head off court servant' is the wordplay.
'claim' becomes 'aver' (I've seen this before).
'head off' means to remove the first letter.
'court servant' becomes 'page'.
'page' with its initial letter taken away is 'age'.
'aver'+'age'='AVERAGE'
'to' is the link.
(Other definitions for average that I've seen before include "Arithmetic mean" , "Mean - ordinary" , "Fair to middling" , "Normal; mean" , "Medium; normal" .)