Lacking money, possibly shy (5)
I believe the answer is:
short
This clue could be a double definition.
'lacking money' is the first definition.
'short' can be an answer for 'lacking' (thesaurus). I'm not sure about the 'money' bit.
'shy' is the second definition.
(thesaurus)
'possibly' is the link.
Can you help me to learn more?
(Other definitions for short that I've seen before include "Small in height" , "Terse; in insufficient supply" , "Of small length" , "Not long enough" , "Literary genre such as those by ..." .)