Official marks popular gain and is made to look daft (8)
I believe the answer is:
insignia
'official marks' is the definition.
'popular gain and is made to look daft' is the wordplay.
'popular' becomes 'in'.
'and' means one lot of letters go next to another.
'made to look daft' is an anagram indicator.
'gain'+'is'='gainis'
'gainis' with letters rearranged gives 'signia'.
'in'+'signia'='INSIGNIA'
(Other definitions for insignia that I've seen before include "Badge or emblems of office" , "Badge of membership" , "I sign in a funny way to get badges or emblems" , "arms" , "Badge worn to show official position" .)