Unfortunately a pest will eat little plant (5,3)
I believe the answer is:
sweet pea
'plant' is the definition.
(sweet pea is a kind of plant)
'unfortunately a pest will eat little' is the wordplay.
'unfortunately' indicates anagramming the letters.
'will eat' indicates putting letters inside.
'little' becomes 'wee' ('wee' can be similar in meaning to 'little'**).
'a'+'pest'='apest'
'apest' with letters rearranged gives 'stpea'.
'stpea' enclosing 'wee' is 'SWEET PEA'.
(Other definitions for sweet pea that I've seen before include "flowering plant" , "Fragrant bloom" , "Perfumed climber" , "bloomer" , "Fragrant flower" .)