Thread or line attached to card (4)
I believe the answer is:
lace
'thread' is the definition.
(thesaurus)
'line attached to card' is the wordplay.
'line' becomes 'l'.
'attached to' means one lot of letters go next to another.
'card' becomes 'ace' (I've seen this before).
'l'+'ace'='LACE'
'or' acts as a link.
(Other definitions for lace that I've seen before include "Shoe tie" , "Shoestring: delicate ornamental fabric" , "Spike - ornamental fabric" , "Shoe cord" , "Fine needlework" .)