Material girl, eager (7)
I believe the answer is:
nankeen
'material' is the definition.
(nankeen is a kind of material)
'girl eager' is the wordplay.
'girl' becomes 'nan'.
'eager' becomes 'keen' (I've seen this before).
'nan'+'keen'='NANKEEN'
(Other definitions for nankeen that I've seen before include "Hard-wearing fabric, originally from China" , "Yellowish cotton cloth" , "Buff-coloured cotton fabric" , "Chinese cotton cloth" , "Buff colour" .)