Except for the L in “balm” (5)
I believe the answer is:
salve
'balm' is the definition.
(I know that balm can be written as salve)
'except for the l in' is the wordplay.
'except for' becomes 'save' (I've seen this in another clue).
'in' indicates putting letters inside.
'save' placed around 'l' is 'SALVE'.
(Other definitions for salve that I've seen before include "Laves with soothing stuff" , "Soother" , "Roman greeting" , "Soothing remedy" , "One rubbed on skin" .)