Colin worried about notes being short (7)
I believe the answer is:
laconic
'short' is the definition.
(synonyms)
'colin worried about notes' is the wordplay.
'worried' is an anagram indicator (worry can mean to interfere with or disturb).
'about' is an insertion indicator.
'notes' becomes 'ac'.
'colin' with letters rearranged gives 'lonic'.
'lonic' enclosing 'ac' is 'LACONIC'.
'being' is the link.
(Other definitions for laconic that I've seen before include "without verbosity" , "Succinct in speech" , "'Curt, terse (7)'" , "without many words" , "Using few words, terse" .)