Wise man with small gold crown making something for breakfast (7)
I believe the answer is:
sausage
'something for breakfast' is the definition.
(sausages are often eaten as part of a breakfast)
'wise man with small gold' is the wordplay.
'wise man' becomes 'sage' (sage is a kind of wise man).
'with' means one lot of letters go next to another.
'small' becomes 's' (abbreviation - e.g. clothes size).
'gold' becomes 'Au' (Au is the chemical symbol for gold).
's'+'au'='sau'
'sage' after 'sau' is 'SAUSAGE'.
'crown making' acts as a link.
This may not be correct. Some or all of it may be part of another bit of the clue.
(Other definitions for sausage that I've seen before include "sort of roll?" , "Not a - means nothing" , "BBQ food?" , "Chipolata, for example" , "Assuage (anag.)" .)