Nice friend supporting one in organisation that's folding? (7)
I believe the answer is:
origami
'folding?' is the definition.
(origami involves folding)
'nice friend supporting one in organisation' is the wordplay.
'nice friend' becomes 'ami' ('friend' in French - Nice is in France).
'supporting' says to put letters next to each other (in a down clue, some letters go below others).
'one' becomes 'i' (Roman numeral).
'in' means one lot of letters goes inside another.
'organisation' becomes 'org' (common abbreviation).
'i' placed into 'org' is 'orig'.
'ami' put after 'orig' is 'ORIGAMI'.
'that's' is the link.
(Other definitions for origami that I've seen before include "Making of paper shape" , "Paperwork, as it were" , "Japanese art of folding or tearing paper" , "Art originally created in simple materials to design bird forms" , "Eastern art" .)