Lined beach and pier up? Impossible to work out (14)
I believe the answer is:
indecipherable
'impossible to work out' is the definition.
I can't judge whether this definition defines the answer.
'lined beach and pier up?' is the wordplay.
'and' says to put letters next to each other.
'up?' indicates anagramming the letters (I've seen 'up' mean this (letters get chucked up)).
'lined'+'beach'+'pier'='linedbeachpier'
'linedbeachpier' is an anagram of 'INDECIPHERABLE'.
Can you help me to learn more?
(Another definition for indecipherable that I've seen is " not good for readers".)