Criticise when Lisa gets upset (6)
I believe the answer is:
assail
'criticise' is the definition.
(I know that assail is a type of criticise)
'when lisa gets upset' is the wordplay.
'when' becomes 'as' (eg 'when I walked' means 'as I walked').
'gets upset' indicates anagramming the letters (I've seen 'getting upset' mean this).
'lisa' with letters rearranged gives 'sail'.
'as'+'sail'='ASSAIL'
(Other definitions for assail that I've seen before include "Beset" , "Launch an attack" , "Attack, lash out" , "Slate" , "Molest or harass" .)