Eccentric daughter in golf club (7)
I believe the answer is:
dingbat
'eccentric' is the definition.
'daughter in golf club' is the wordplay.
'daughter' becomes 'd' (genealogical abbreviation).
'golf' becomes 'g' (phonetic alphabet: alpha, bravo, charlie etc.).
'club' becomes 'bat' (as in sporting equipment).
'd'+'in'+'g'+'bat'='DINGBAT'
(Other definitions for dingbat that I've seen before include "Simpleton" , "funny-looking character" , "plonker" , "Aussie fool" , "Idiot" .)