Garden bulb (5)
'garden bulb' is the definition.
(I've seen this in another clue)
This is all the clue.
(Other definitions for tulip that I've seen before include "Flower - lit up (anag)" , "Spring bulb" , "Plant of the lily family with a single showy flower" , "Plant at the centre of the Dutch financial bubble of 1637" , "Bulb producing a single showy flower" .)
(Other definitions for crocus that I've seen before include "Early flowering bulb" , "Plant from a corm" , "Yellow, purple or white spring flower" , "Spring plant" , "Spring-flowering plant" .)