Popular taste one day becomes uninteresting (7)
I believe the answer is:
insipid
'uninteresting' is the definition.
(similar in meaning)
'popular taste one day' is the wordplay.
'popular' becomes 'in' ('in' can mean trendy).
'taste' becomes 'sip' (I've seen this in another clue).
'one' becomes 'i' (Roman numeral).
'day' becomes 'd' (abbreviation for day).
'in'+'sip'+'i'+'d'='INSIPID'
'becomes' acts as a link.
(Other definitions for insipid that I've seen before include "Bland, flavourless" , "Lacking taste or flavour" , "Dull" , "Very weak" , "Colourless" .)