Line on map? I like that Rod! (6)
I believe the answer is:
isobar
'line on map?' is the definition.
(I've seen this before)
'i like that rod' is the wordplay.
'like that' becomes 'so' (I've seen this in other clues).
'rod' becomes 'bar' (I've seen this before).
'i'+'so'+'bar'='ISOBAR'
(Other definitions for isobar that I've seen before include "sign of pressure" , "Contour" , "curve on map" , "What's shown on some maps" , "It indicates pressure" .)