Clubs: golfer's one mistakenly dropped (7)
I believe the answer is:
clanger
'one mistakenly dropped' is the definition.
I can't tell whether this defines the answer.
'clubs golfer's' is the wordplay.
'clubs' becomes 'c' (abbreviation used in card games such as bridge).
'golfer' becomes 'langer' (Bernhard Langer).
'c'+'langer'='CLANGER'
Can you help me to learn more?
(Other definitions for clanger that I've seen before include "Big blunder" , "Bad mistake - loud bell" , "One ringing" , "Bell possibly" , "noise that rings in the ear" .)