Sewing aid (7)
'sewing aid' is the definition.
(I've seen this in another clue)
This is all the clue.
(Other definitions for thimble that I've seen before include "Digital protection" , "Finger protection when sewing" , "Sewer's protection" , "Protective item for the tailor" , "Sewer's protector" .)
(Other definitions for pin that I've seen before include "Skittle; chess attack" , "form of identification" , "Fastener; skittle" , "Debit-card number" , "leg" .)