Part of leg making the head tall (5)
I believe the answer is:
thigh
'part of leg' is the definition.
('thigh' is part of 'leg')
'the head tall' is the wordplay.
'head' suggests taking the first letters.
'tall' becomes 'high' (similar in meaning).
The initial letter of 'the' is 't'.
't'+'high'='THIGH'
'making' acts as a link.
(Other definitions for thigh that I've seen before include "Part of member" , "Leg between knee and hip" , "Upper part of the leg" , "Upper joint of the leg" , "part of body" .)