Informed singular desire shows an increase (7)
I believe the answer is:
upsurge
'an increase' is the definition.
(I know that upsurge is a type of increase)
'informed singular desire' is the wordplay.
'informed' becomes 'up' (being up on a topic means being informed about it).
'singular' becomes 's' (abbreviation in grammar).
'desire' becomes 'urge' (I've seen this in another clue).
'up'+'s'+'urge'='UPSURGE'
'shows' acts as a link.
(Other definitions for upsurge that I've seen before include "Sudden forceful flow from below" , "growth" , "Sudden or abrupt strong increase" , "A sudden rise, as in business" , "Sudden rapid increase" .)