Having the capacity to live without a drop of refreshing fluid (8)
I believe the answer is:
variable
'having the capacity to live' is the definition.
I can't tell whether this defines the answer.
'without a drop of refreshing fluid' is the wordplay.
'without' is an insertion indicator.
'drop of' says to take the initial letters.
'fluid' becomes 'viable' (I can't justify this - if you can you should believe this answer much more).
The initial letter of 'refreshing' is 'r'.
'a'+'r'='ar'
'ar' inserted inside 'viable' is 'VARIABLE'.
Can you help me to learn more?
(Other definitions for variable that I've seen before include "Subject to change" , "Prone to change" , "Not consistent, without a fixed pattern" , "Unsteady" , "Inconsistent" .)