Ten of the eleven unclued lights are of a kind and consist of singleton of two words, three pairs and a trio. The eleventh unclued is thematic when paired with an anagram of the five highlighted red letters. Elsewhere, ignore an apostrophe and an accent.

Across

4 Talked of mark on potato magazine (9)
11 Little girl, outside in the morning, is wandering (5)
14 Fabric — some linen? — on inventory (5)
15 One clad in extra silk (5)
16 Service of diplomat in Serbia (6)
21 Difficult situation having coarse flax by joint (8)
22 Descent, using a rope, perhaps, taking time (7)
24 Still...