Crossword Genius

A peer films erratic guides having their ups and downs (6,4)

Ross

I believe the answer is:

relief maps

'guides having their ups and downs' is the definition.
(maps showing depth)

'a peer films erratic' is the wordplay.
'erratic' indicates anagramming the letters.
'a'+'peer'+'films'='apeerfilms'
'apeerfilms' is an anagram of 'RELIEF MAPS'.

I've seen this clue in The Times.
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