A herb that may be used in healthy meal (5)
I believe the answer is:
thyme
'a herb' is the definition.
(thyme is a kind of herb)
'used in healthy meal' is the wordplay.
'used in' indicates the answer is hidden within the clue.
'THYME' is hidden in the letters of 'healthy meal'.
'that may be' is the link.
(Other definitions for thyme that I've seen before include "Herb with fragrant leaves - parsley, sage, rosemary and . . . . ." , "Aromatic ingredient" , "Aromatic shrub" , "Shrub - herb" , "Small shrub: leaves used to season food" .)