For Slim, within range, could be a dangerous moment (4,5)
I believe the answer is:
near thing
'for slim' is the definition.
I can't judge whether this defines the answer.
'within range could be a dangerous moment' is the wordplay.
'within' indicates putting letters inside.
'could be' indicates anagramming the letters.
'a dangerous moment' becomes 'thin' (I am not sure about this - if you are sure you should believe this answer much more).
'range' is an anagram of 'nearg'.
'nearg' going around 'thin' is 'NEAR THING'.
Can you help me to learn more?
(Other definitions for near thing that I've seen before include "Lucky escape" , "Narrow escape, close shave" , "Something that barely avoids failure or disaster" , "dangerous" , "Even the short-sighted could plainly see that" .)