Line secured by camping expert? It often flaps about (8)
I believe the answer is:
tentacle
'it often flaps about' is the definition.
The definition suggests a singular noun which matches the answer.
'line secured by camping expert?' is the wordplay.
'line' becomes 'l' (used when specifying particular lines from a poem).
'secured by' is an insertion indicator (inserted letters are held or secured).
'camping' becomes 'tent' (I've seen this in other clues).
'expert?' becomes 'ace' (ace can informally mean very good).
'tent'+'ace'='tentace'
'l' inserted inside 'tentace' is 'TENTACLE'.
Can you help me to learn more?
(Other definitions for tentacle that I've seen before include "Slender flexible limb" , "Flexible appendage on some animals" , "Long flexible feeler" , "Flexible grasping organ" , "Octopus's "arm"" .)