Design provided following test (5)
I believe the answer is:
motif
'design' is the definition.
(I know that motif is a type of design)
'provided following test' is the wordplay.
'provided' becomes 'if' (eg 'provided it's sunny' means 'if it's sunny').
'following' means one lot of letters go next to another.
'test' becomes 'MOT' (MOT test).
'if' put after 'mot' is 'MOTIF'.
(Other definitions for motif that I've seen before include "decoration" , "Logo -- pattern" , "Recurring image in design" , "Theme in music or book" , "Theme or melody" .)