Fixed small meal at beginning and end of day (6)
I believe the answer is:
steady
'fixed' is the definition.
(thesaurus)
'small meal at beginning and end of day' is the wordplay.
'small' becomes 's' (abbreviation - e.g. clothes size).
'meal' becomes 'tea' (tea is a kind of meal).
'at' is a charade indicator (letters next to each other).
'beginning and end of' suggests removing the centre.
'day' with its middle removed is 'dy'.
's'+'tea'+'dy'='STEADY'
(Other definitions for steady that I've seen before include "Firm or constant" , "Stable - boyfriend or girlfriend" , "Reliable, unvarying" , "Hey" , "Well secured" .)