Most of group left lake in sudden storm (6)
I believe the answer is:
squall
'sudden storm' is the definition.
(I've seen this before)
'most of group left lake' is the wordplay.
'most of' means to remove the last letter.
'group' becomes 'squad'.
'left lake' becomes 'll' (this could be a standard abbreviation which I don't know about).
'squad' with its final letter taken away is 'squa'.
'squa'+'ll'='SQUALL'
'in' acts as a link.
Can you help me to learn more?
(Other definitions for squall that I've seen before include "Sudden brief storm" , "Sudden storm of wind and rain, or a baby's cry" , "Brief violent storm" , "Short-lived violent gust of wind and rain" , "Sudden violent gust of wind" .)