Field northwards contains garland of flowers (3)
I believe the answer is:
lei
'garland of flowers' is the definition.
(garland of flowers worn in Polynesia)
'field northwards contains' is the wordplay.
'contains' indicates the answer is hidden within the clue.
'northwards' is a reversal indicator (in a down clue, letters go up or 'north').
'iel' is hidden within 'field'.
'iel' back-to-front is 'LEI'.
(Other definitions for lei that I've seen before include "Hawaiian necklace of flowers" , "change in E. Europe" , "Hawaiian flower garland" , "Necklace of tropical flowers" , "Flower arrangements" .)