Same sort of join (4)
I believe the answer is:
seam
'join' is the definition.
(I know that seam is a more specific form of join)
'same sort' is the wordplay.
'sort' indicates anagramming the letters.
'same' is an anagram of 'SEAM'.
'of' acts as a link.
(Other definitions for seam that I've seen before include "Stitched joint" , "Join - thin layer" , "Joint between two edges" , "Join round cricket ball" , "Underground layer of mineral" .)